In a conventional memory system in which a host device and one or more nonvolatile memory devices are connected to each other, the host device generates commands and the nonvolatile memory devices perform various communication processes in response to the commands. When this memory system is booted, the host device is required to read a program for boot-up, which is called a boot code, from the nonvolatile memory devices connected in the system. Although the boot code has conventionally been stored in a NOR flash memory, the code is now often stored in a NAND flash memory or a nonvolatile memory device including a NAND flash memory, which tends toward a larger capacity and a lower cost. The boot code is then read from the NAND flash memory or the nonvolatile memory device including the NAND flash memory when the system is booted. Data is typically read from or written to the NAND flash memory or the nonvolatile memory device including the NAND flash memory using commands. The process of reading the boot code needs to be performed during system start-up when software is not yet activated. The memory system thus needs the simplest method to read the boot code.
For example, Patent Literature 1 describes a technique for reading, during boot-up, a boot code from a device having an SD/MMC interface using a signal line for a command defined by the SD/MMC interface.